JP7736264B2 - Polyester resin and method for producing polyester resin - Google Patents

Description

The present invention relates to a polyester resin that can maintain good water repellency even after long-term use.

Polyester resins have excellent properties such as heat resistance, dimensional stability, and mechanical properties, and are therefore widely used in a variety of fields, including fibers, films, and molded articles. To impart properties such as water repellency, it is known that fibers or fabrics made of polyester resins are treated with a dispersion containing a water-repellent resin such as a fluorine-based resin or silicone-based resin, thereby adhering the resin to the surface (see, for example, Patent Document 1).

Japanese Patent Application Publication No. 5-106171

As in Patent Document 1, the water repellency imparted by surface treatment has the drawback of being low in durability, with the water repellency decreasing with long-term use, repeated washing, etc. Furthermore, if surface treatment is performed using an amount of resin that would impart sufficient water repellency durability, there are problems with the resulting fibers, films, etc., becoming hard in texture and rough to the touch.

In light of these current circumstances, the object of the present invention is to provide a polyester resin that, when molded into fibers, films, and other molded products, has excellent water-repellent properties without the need for water-repellent treatment, and has excellent water-repellent durability (water-repellent durability).

As a result of extensive research into the problems of the prior art, the inventors discovered that the above objectives could be achieved if the polyester was copolymerized with silicone within a specific range and the copolymerized silicone had a high reactivity, leading to the completion of the present invention.

That is, the gist of the present invention is as follows.
(1) A polyester resin comprising a polyester composed of an aromatic dicarboxylic acid and an aliphatic diol and containing silicone, wherein 90% or more of the silicone is copolymerized with the polyester, the content of the copolymerized silicone in the polyester resin is 1 to 60% by mass, and the polyester resin has an intrinsic viscosity of 0.5 to 0.8 .
(2) Fibers containing the polyester resin of (1) .
(3) A film containing the polyester resin of (1) .
(4) A molded article containing the polyester resin of (1) .
(5) A resin solution containing the polyester resin of (1) .
(6) Powder containing the polyester resin of (1) .
(7) A method for producing a polyester resin by carrying out an esterification reaction and a polycondensation reaction, comprising adding to a mixture of a polyester raw material and a silicone:
A tin-based esterification catalyst is added in an amount of 1×10 ⁻⁵ to 1×10 ⁻⁴ mol per mol of the total acid components of the polyester, and an esterification reaction is carried out at a reaction temperature of 250 to 270° C.,
A method for producing a polyester resin, comprising adding 1×10 ⁻⁵ to 1×10 ⁻⁴ mol of a polycondensation catalyst per 1 mol of the total acid components of the polyester, and carrying out a polycondensation reaction at a reaction temperature of 250 to 270°C.

The polyester resin of the present invention has excellent water repellency and water repellency durability.

The present invention will be described in detail below.
The polyester resin of the present invention is a polyester made from an aromatic dicarboxylic acid and an aliphatic diol, and further contains silicone.

The aromatic dicarboxylic acid in the polyester resin of the present invention preferably contains terephthalic acid as a primary component. The content of terephthalic acid in the total acid components is preferably 80 mol% or more, and more preferably 90 mol% or more. If the terephthalic acid content is less than 80 mol%, the crystallinity and heat resistance may be poor.

Examples of acid components other than terephthalic acid in the polyester resin of the present invention include isophthalic acid, phthalic acid, phthalic anhydride, naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, dodecanedioic acid, and dimer acids. Two or more of these may be used in combination, and ester-forming derivatives of these acids may also be used.

The aliphatic diol in the polyester resin of the present invention preferably contains ethylene glycol as a main component. The ethylene glycol content of the total aliphatic diols is preferably 80 mol% or more, and more preferably 90 mol% or more. If the ethylene glycol content is less than 80 mol%, the crystallinity and heat resistance may be poor.

Aliphatic diol components other than ethylene glycol in the polyester resin of the present invention include, for example, diethylene glycol, neopentyl glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexamethylenediol, 1,4-cyclohexanedimethanol, and dimer diol. Two or more of these may be used in combination.

In the polyester resin of the present invention, the content of silicone copolymerized with the polyester resin is 1 to 60% by mass, preferably 2 to 40% by mass, and more preferably 3 to 30% by mass. If the content of silicone copolymerized with the polyester is less than 1% by mass, the water repellency and water repellency durability will be poor. On the other hand, if the content of silicone copolymerized with the polyester exceeds 60% by mass, the operability will be poor, for example, when attempting to obtain fibers from the polyester resin of the present invention.

In the polyester resin of the present invention, 90% or more of the silicone is copolymerized with the polyester, preferably 98% or more, and more preferably 100%. In other words, the reaction rate of the silicone copolymerized with the polyester is 90% or more, preferably 98% or more, and more preferably 100%.
By ensuring that the reactivity of silicone with polyester resin is in a high range of 90% or more, it is possible to suppress broken yarns during spinning and improve operability, and to suppress defects in appearance when a molded article is produced, and further to achieve excellent water repellency durability.

In the present invention, the reaction rate (copolymerization rate) is calculated by the following formula.
Reaction rate of silicone (%)=((mass of copolymerized silicone/(total mass of copolymerized silicone and unreacted silicone)))×100
The method for determining the mass of copolymerized silicone and the mass of unreacted silicone will be described in detail in the Examples.

In the polyester resin of the present invention, an example of the silicone that has reacted with the polyester and copolymerized is shown in the following chemical formula (1). Furthermore, an example of the unreacted silicone that has not copolymerized with the polyester is shown in the following chemical formula (2).

In chemical formula (1) and chemical formula (2), ^R1 is preferably an alkyl group having 1 to 10 carbon atoms or a phenyl group, and may be the same or different. Among these, a methyl group or an ethyl group is preferred from the viewpoint of small steric hindrance and good reactivity with polyester.
In chemical formula (1) and chemical formula (2), R is a divalent organic group.

In chemical formula (1) and chemical formula (2), n is preferably an integer from 1 to 100, more preferably an integer from 2 to 50, and even more preferably an integer from 3 to 30. If n is an integer of 101 or greater, reactivity with the ester may decrease. On the other hand, if n is 0, it may be difficult to impart silicone-derived properties to the polyester, and water repellency and water repellency durability may be poor.

In chemical formula (2), X represents a substituent capable of forming an ester, and may be the same or different. Examples of X include amino groups, epoxy groups, alicyclic epoxy groups, carbinol groups, methacryl groups, polyether groups, mercapto groups, carboxyl groups, phenol groups, silanol groups, acrylic groups, carboxylic anhydride groups, polyethylene oxide groups, and polypropylene oxide groups. Among these, carbinol groups, carboxyl groups, and polyether groups are preferred from the standpoint of reactivity with polyesters.

Examples of silicones represented by chemical formula (2) include silicones modified with carbinol groups, silicones modified with carboxyl groups, silicones modified with polyether groups, silicones modified with epoxy groups, silicones modified with silanol groups, and silicones modified with carboxylic acid anhydrides. Among these, silicones modified at both ends with carbinol groups, silicones modified at both ends with carboxyl groups, and silicones modified at both ends with polyether groups are more preferred from the standpoint of reactivity with polyester.

The intrinsic viscosity of the polyester resin of the present invention is preferably 0.5 to 0.80, and more preferably 0.50 to 0.75. If the intrinsic viscosity is less than 0.5, when fibers are obtained from the polyester resin of the present invention, the strength will be low and workability will be impaired. On the other hand, if the intrinsic viscosity exceeds 0.80, handling may be impaired. The intrinsic viscosity is measured at a temperature of 20°C using an equal weight mixture of phenol and tetrachloroethane as the solvent.

The polyester resin of the present invention may contain various additives, such as other resins, heat stabilizers, antioxidants, reinforcing materials, pigments, antidegradants, weather resistance agents, flame retardants, plasticizers, preservatives, UV absorbers, antistatic agents, and antiblocking agents, as needed, provided that the properties of the resin are not impaired. These additives may be used alone or in combination of two or more.

The polyester resin of the present invention may also contain titanium oxide, which is commonly used as a matting agent or white pigment, in order to improve the whiteness of the resulting fiber and produce a fabric with a good color tone. The titanium oxide content is preferably 0.05 to 5 parts by mass per 100 parts by mass of the polyester resin of the present invention.

Next, the method for producing the polyester resin of the present invention will be described below.
The polyester resin of the present invention is produced by carrying out an esterification reaction and a polycondensation reaction.
First, a mixture of polyester raw material and silicone, and a tin-based esterification catalyst are placed in an arbitrary esterification reactor, and an esterification reaction is carried out.

Polyester raw materials include aliphatic diols such as ethylene glycol, diethylene glycol, neopentyl glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexamethylenediol, 1,4-cyclohexanedimethanol, and dimer diol, and aromatic dicarboxylic acid components such as terephthalic acid, isophthalic acid, phthalic acid, phthalic anhydride, naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, dodecanedioic acid, and dimer acids.

Ethylene terephthalate oligomer can also be used as a polyester raw material. Known or commercially available ethylene terephthalate can be used. It can also be produced by known production methods.

In particular, the ethylene terephthalate oligomer may preferably be, for example, an esterification reaction product of ethylene glycol and terephthalic acid. The number-average degree of polymerization of the ethylene terephthalate oligomer is not particularly limited, but can be, for example, approximately 2 to 20.

The silicone used in the manufacturing method of the present invention includes the silicone represented by the above chemical formula (2). The molecular weight of the silicone is preferably 500 to 10,000, and more preferably 900 to 6,000. If the molecular weight is less than 500, the resulting polyester resin may have poor water repellency, while if it exceeds 10,000, the reaction between the silicone and the polyester may not proceed smoothly, leaving a large amount of unreacted silicone in the polyester, which may reduce the reaction rate.

In the production method of the present invention, by using a tin-based esterification catalyst as the esterification catalyst, the esterification reaction between silicone and polyester proceeds more rapidly, leaving less unreacted silicone, and allowing for the production of a polyester resin with excellent water repellency, compared to polyester resins produced using other esterification catalysts (e.g., titanium-based esterification catalysts).

Tin-based esterification catalysts include mono-n-butyltin oxide, tetrabutyltin, butylchlorotin dihydroxy, butyltris-2-ethylhexanoate, tin oxalate, and dimethyltin maleate. Mono-n-butyltin oxide is preferred in terms of reactivity between silicone and polyester.

In the method for producing a polyester resin of the present invention, the amount of tin-based esterification catalyst added is 1×10 ⁻⁵ to 1×10 ⁻⁴ mol, preferably 2×10 ⁻⁵ to 6×10 ⁻⁵ mol%, per mol of the total acid components of the polyester. If the amount of tin-based esterification catalyst added is small and outside this range, the reaction between the polyester raw material and silicone does not proceed, resulting in the presence of unreacted silicone in the resin, and a decrease in the reaction rate. As a result, the unreacted silicone becomes a foreign substance, and when attempting to obtain fibers using the polyester resin, thread breakage is likely to occur during spinning, or when attempting to obtain molded products, appearance defects and the like are likely to occur. Furthermore, when the polyester resin is made into fibers, the water repellency durability is reduced.
On the other hand, if the amount of tin-based esterification catalyst added is greater than this range, the silicone will decompose during the reaction, and the decomposed silicone will become a foreign substance in the resin. As a result, thread breakage will be more likely to occur during spinning, and defects in appearance will be more likely to occur when attempting to obtain a molded product. Furthermore, when the resin is made into fibers, etc., the water-repellent durability will decrease.

In the method for producing a polyester resin of the present invention, the esterification reaction temperature is 250 to 270°C, and preferably 255 to 265°C.
If the reaction temperature is lower than this range, the reaction between the polyester raw material and the silicone will not proceed, and unreacted silicone will remain in the resin, resulting in a decrease in the reaction rate. As a result, the unreacted silicone will become a foreign substance, and as a result, when attempting to obtain fibers using the obtained polyester resin, thread breakage will be more likely to occur during spinning, and when attempting to obtain molded products, appearance defects will be more likely to occur. Furthermore, when made into fibers, etc., the water repellency durability will be reduced.
On the other hand, if the reaction temperature is higher than this range, the silicone will decompose during the reaction and the decomposed silicone will become contained in the resin and become a foreign substance, and as a result, when an attempt is made to obtain fibers using the polyester resin, thread breakage will be more likely to occur during spinning, and when an attempt is made to obtain a molded product, appearance defects will be more likely to occur, etc. Furthermore, when the polyester resin is made into fibers, etc., the water repellency durability will be reduced.

After the esterification reaction is complete, the resulting ester is transferred to a polycondensation reactor of your choice, where a polycondensation catalyst is added to carry out the polycondensation reaction. Examples of polycondensation catalysts include antimony-based polycondensation catalysts and titanium-based polycondensation catalysts. Of these, titanium-based polycondensation catalysts are preferred, as they allow the polycondensation reaction of silicone copolyester to proceed in a relatively short time, resulting in a high silicone reaction rate and enabling the production of a polyester resin with excellent water-repellent durability.

In the method for producing a polyester resin of the present invention, the amount of polycondensation catalyst added is 1×10 ⁻⁵ to 1×10 ⁻⁴ mol, preferably 2×10 ⁻⁵ to 6×10 ⁻⁵ mol, per mol of the total acid components of the polyester. If the amount of polycondensation catalyst added is less than this range, the reaction between the polyester raw material and the silicone does not proceed, resulting in the presence of unreacted silicone in the resin, and a decrease in the reaction rate. As a result, the unreacted silicone becomes a foreign substance, and when the obtained resin is used to produce fibers, breakage of the yarn is likely to occur during spinning, or defects in appearance occur when the resin is produced into a molded article. Furthermore, when the resin is produced into fibers, the water repellency durability decreases.
On the other hand, if the amount of polycondensation catalyst added is greater than this range, the silicone will be decomposed during the reaction, and the decomposed silicone will be contained in the resin and become foreign matter.As a result, when the obtained resin is used to make fibers, thread breakage will easily occur during spinning, or when a molded product is made, appearance defects etc. will occur.In addition, when made into fibers, the water repellency durability will decrease.

In the method for producing a polyester resin of the present invention, the polycondensation reaction is carried out at a temperature of 250 to 270°C, preferably 255 to 265°C.
If the reaction temperature is lower than this range, the reaction between the polyester raw material and the silicone does not proceed, and unreacted silicone remains in the resin, resulting in a decrease in reaction rate. As a result, the unreacted silicone becomes a foreign substance, and when the obtained resin is used to make fibers, breakage is likely to occur during spinning, or when a molded product is made, defects in appearance and the like occur. Also, when the resin is made into fibers, the water-repellent durability is reduced. On the other hand, if the reaction temperature is higher than this range, the silicone is decomposed during the reaction, and the decomposed silicone is contained in the resin and becomes a foreign substance. As a result, when the obtained resin is used to make fibers, breakage is likely to occur during spinning, or when a molded product is made, defects in appearance and the like occur. Also, when the resin is made into fibers, the water-repellent durability is reduced.

The polycondensation reaction is preferably carried out at a pressure in the reactor of 1.0 hPa or less. If the pressure during the polycondensation reaction exceeds 1.0 hPa, the polycondensation reaction time will be longer, which may result in poor productivity.

During the polycondensation reaction, if necessary, a hindered phenol-based antioxidant can be added in addition to the above-mentioned polymerization catalyst, or a phosphorus compound can be added to suppress thermal decomposition of the resin.

Examples of hindered phenol antioxidants include 2,6-di-t-butyl-4-methylphenol, n-octadecyl-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate, tetrakis[methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]methane, tris(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate, 4,4'-butylidenebis-(3-methyl-6-t-butylphenol), tris(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate, and 4,4'-butylidenebis-(3-methyl-6-t-butylphenol). Examples of compounds that can be used include ethylene glycol-bis[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionate] and 3,9-bis{2-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1'-dimethylethyl}-2,4,8,10-tetraoxaspiro[5,5]undecane, but from the standpoint of effectiveness and cost, tetrakis[methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]methane is preferred. These can be used alone or in combination of two or more.

Examples of phosphorus compounds that can be used include phosphorous acid, phosphoric acid, trimethyl phosphite, triphenyl phosphite, tridecyl phosphite, trimethyl phosphate, tridecyl phosphate, and triphenyl phosphate. These compounds can be used alone or in combination of two or more.

Applications of the polyester resin of the present invention include, but are not limited to, fibers, films, molded articles, resin solutions, powders, etc. For each application, the polyester resin of the present invention can be used alone or in combination with other resin compositions, etc., and can be processed using known manufacturing techniques.

When fibers are obtained using the polyester resin of the present invention, not only can the entire single fiber be formed from the polyester resin of the present invention, but also composite fibers can be obtained from the polyester resin of the present invention and a resin composition other than the polyester resin of the present invention (for example, a polyester resin containing inorganic particles such as titanium dioxide in addition to a polyethylene terephthalate resin or a polyester resin containing other copolymer components). Examples of composite fiber configurations include sheath-core, side-by-side, and islands-in-sea. For example, when obtaining sheath-core fibers using the polyester resin of the present invention, it is preferable to use the polyester resin of the present invention in the sheath portion from the perspective of water repellency. In this case, the mass ratio of the core to the sheath portion (core/sheath) is preferably 60/40 to 90/10.

The present invention will now be described in detail with reference to examples, in which the measurement and evaluation methods for various properties and the like are as follows.
(a) Intrinsic Viscosity Using the obtained polyester resin, a mixture of equal masses of phenol and tetrachloroethane was used as a solvent, and the intrinsic viscosity was measured at a temperature of 20° C. by a known method.

(b) Silicone Content and Reaction Rate in Polyester Resin The obtained polyester resin was dissolved in hexafluoroisopropanol, deuterated tetrachloroethane was added, and the mixture was heated to 130° C. to remove the hexafluoroisopropanol.
Thereafter, ¹ H-NMR was measured using a JNM-ECZ400R/S1 NMR apparatus manufactured by JEOL Ltd. The content of copolymerized silicone was determined from the integrated intensity of the proton peaks of each component in the resulting chart (terephthalic acid peak (δ: approximately 8.0 ppm), ethylene glycol peak (δ: approximately 4.6 ppm), diethylene glycol peak (δ: approximately 3.8 ppm)) and the proton peaks in the silicone copolymerized by the reaction.

The reaction rate of silicone was calculated from the mass of copolymerized silicone and the mass of unreacted silicone using the following formula:
Reaction rate of silicone (%)=(mass of copolymerized silicone/(total mass of copolymerized silicone and unreacted silicone)×100

The mass of copolymerized silicone and the mass of unreacted silicone were determined as follows.
In Examples 1 to 8 and 11 and Comparative Examples 1 to 11, the masses of the copolymerized silicone and the unreacted silicone were determined from the integrated intensity of the proton peak (δ: approximately 3.5 ppm) representing both the silicone that had reacted with the polyester and been copolymerized and the unreacted silicone, and the proton peak (δ: approximately 0.5 ppm) representing only the unreacted silicone.

In Example 9, the masses of the copolymerized silicone and the unreacted silicone were determined from the integrated intensity of the proton peak (δ: approximately 0.9 ppm) representing the silicone that had reacted with the polyester and been copolymerized, and the proton peak (δ: approximately 0.8 ppm) representing the unreacted silicone.
In Example 10, the masses of the copolymerized silicone and the unreacted silicone were determined from the integrated intensity of the proton peak (δ: approximately 0.5 ppm) representing both the silicone that had reacted with the polyester and been copolymerized and the unreacted silicone, and the proton peak (δ: approximately 5.2 ppm) representing only the unreacted silicone.

(c) Molecular Weight of Silicone The molecular weight of the silicone used in the examples and comparative examples was calculated from the hydroxyl value (mg KOH/g) and functional group equivalent (g/mol).

(d) Contact angle A sheet having a thickness of 0.2 mm was produced from the obtained polyester resin using a gel counter manufactured by OCS under the conditions of an extruder temperature of 260 to 290°C, a rotation speed of 130 rpm, a winder temperature of 30 to 50°C, and a rotation speed of 2 m/min. The contact angle of this sheet was measured by the sessile drop method using a high-performance automatic contact angle meter DSA30 manufactured by KRUSS. It was determined that the larger the contact angle, the better the water repellency.

(e) Coefficient of kinetic friction, coefficient of static friction The sheet used to measure the contact angle was measured using a friction measuring instrument TR-2 manufactured by Toyo Seiki Seisaku-sho, Ltd., under the conditions of a 200 g plated chrome metal piece, a test speed of 100 mm/min, a test distance of 180 mm, and a measurement environment of 23°C x 50% RH.

(f) Operability (number of yarn breakages)
The obtained polyester resin was melt-spun in a spinning apparatus for 24 hours continuously, and the number of thread breaks per spindle was counted and evaluated as follows.
○: Thread breakage occurred once or less ×: Thread breakage occurred twice or more

(g) Water repellency of fiber Using the obtained cylindrical knitted fabric, evaluation was carried out according to the spray method described in JIS L 1092. Grade 4 or higher was considered to be acceptable.

(h) Water-repellent durability (washing durability)
The obtained cylindrical knitted fabric was washed 10 times (HL10) according to the 103 method described in JIS L 0217, and then the water repellency was evaluated according to the spray method described in JIS L 1092. Grade 4 or higher was considered to be acceptable.

Example 1
A slurry of terephthalic acid (TPA) and ethylene glycol (EG) (TPA/EG molar ratio = 1/1.6) was supplied to an esterification reactor and reacted at a temperature of 250°C and a pressure of 50 hPa to obtain an ethylene terephthalate oligomer (number average degree of polymerization: 5) with an esterification reaction rate of 95%.
To 70 parts by mass of this ethylene terephthalate oligomer, 30 parts by mass of a carbinol-modified silicone represented by the following chemical formula (3) (silicone manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KF-6000", R ² ; CH ₂ CH ₂ CH ₂ -O-CH ₂ CH ₂ , molecular weight = 950) and 5 × 10 ^-5 mol of dimethyltin oxide as a tin-based esterification catalyst per mol of the total acid components were added, and an esterification reaction was carried out at a reaction temperature of 260°C for 2 hours.

The resulting esterification reaction product was then transferred from the esterification reactor to a polycondensation reaction vessel, and 5 × 10 mol of tetrabutyl titanate as a titanium-based polycondensation catalyst was added to the resulting esterification reaction product per mol of the total ^acid components. The pressure was gradually reduced to 1.0 hPa or less after 75 minutes at a reaction temperature of 260°C. Under these conditions, a polycondensation reaction (melt polymerization reaction) was carried out for 5 hours with stirring, yielding a polyester resin with an intrinsic viscosity of 0.68.

[Production of fibers and cylindrical knitted fabrics]
The obtained polyester resin was fed alone to an extruder, and then to a spinning device where it was melt-spun from a spinneret (hole diameter 0.20 mm, 36 spinning holes). After spinning, it was cooled by air flow and passed through an oiling device to apply an oil agent to an amount of adhesion of 0.5% by mass. The mixture was then focused with a focusing guide, entangled, taken up with a roller at a spinning speed of 1400 m/min, and wound up with a winding machine. The obtained fiber (semi-undrawn yarn) was 220 dtex/36f and had no defects such as fluff or single yarn breakage. This was drawn using a conventional drawing device at a speed of 725 m/min, a ratio of 2.77 times, and a temperature of 160 ° C. to obtain a polyester fiber of 80 dtex/36f.
Next, using this polyester fiber, a cylindrical knitted fabric of about 40 cm was made using a cylindrical knitting machine (NDP-01) manufactured by Eiko Sangyo Co., Ltd.

Examples 2 to 7, Comparative Examples 1 to 10
Polyester resins were obtained in the same manner as in Example 1, except that the amount of catalyst added, the esterification reaction temperature, the polycondensation reaction temperature, or the silicone content was changed.
[Production of fibers and cylindrical knitted fabrics]
Polyester fibers and tubular knit fabrics of 80 dtex/36 f were obtained in the same manner as in Example 1, except that the polyester resins obtained in Examples 2 to 7 and Comparative Examples 1 to 10 were used, respectively.

Example 8
A polyester resin was obtained in the same manner as in Example 1, except that the type of silicone was changed to a carbinol-modified silicone shown in formula (3) (silicone manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KF-6001", molecular weight = 1840).
[Production of fibers and cylindrical knitted fabrics]
A polyester fiber and a tubular knit fabric of 80 dtex/36 f were obtained in the same manner as in Example 1, except that the obtained polyester resin was used.

Example 9
A polyester resin was obtained in the same manner as in Example 1, except that the type of silicone was changed to a carboxyl-modified silicone shown in formula (4) (silicone manufactured by Shin-Etsu Chemical Co., Ltd., trade name "X-22-162C", R ³ ; CH ₂ CH ₂ , molecular weight = 2280).
[Production of fibers and cylindrical knitted fabrics]
A polyester fiber and a tubular knit fabric of 80 dtex/36 f were obtained in the same manner as in Example 1, except that the obtained polyester resin was used.

Example 10
A polyester resin was obtained in the same manner as in Example 1, except that the type of silicone was changed to a polyether-modified silicone shown in formula (5) (silicone manufactured by Shin-Etsu Chemical Co., Ltd., trade name "X-22-4952", R ⁴ ; CH ₂ CH ₂ CH ₂ -O, molecular weight = 2240).
[Production of fibers and cylindrical knitted fabrics]
A polyester fiber and a tubular knit fabric of 80 dtex/36 f were obtained in the same manner as in Example 1, except that the obtained polyester resin was used.

Example 11
A polyester resin was obtained in the same manner as in Example 1, except that the reaction time for the polycondensation reaction was changed to 4 hours.
[Production of fibers and cylindrical knitted fabrics]
A polyester fiber and a tubular knit fabric of 80 dtex/36 f were obtained in the same manner as in Example 1, except that the obtained polyester resin was used.

Example 12
[Production of fibers and cylindrical knitted fabrics]
The polyester resin obtained in Example 1 was used as the sheath, and polyethylene terephthalate resin (PET) containing 0.35% by mass of titanium dioxide with an intrinsic viscosity of 0.64 was used as the core. The resulting mixture was fed into an extruder, then into a spinning apparatus, where it was melt-spun from a spinneret (hole diameter 0.35 mm, 48 spinning holes) to produce a concentric sheath-core composite fiber with a core/sheath mass ratio of 85/15. After spinning, the fiber was cooled by airflow and passed through an oiling device to apply an oil to a coating amount of 0.5% by mass. The fiber was then focused using a focusing guide, entangled, and then taken up using a roller at a spinning speed of 3000 m/min and wound on a winder. The resulting fiber (semi-undrawn yarn) had a fineness of 125 dtex/48f and was free of defects such as fluff or single yarn breakage. This was stretched at a speed of 725 m/min, a draw ratio of 1.53 times, and a temperature of 160° C. using a conventional stretching device to obtain a core-sheath bicomponent polyester fiber of 80 dtex/48 f.
Next, using this core-sheath composite polyester fiber, a cylindrical knitted fabric of about 40 cm was made using a cylindrical knitting machine (NDP-01) manufactured by Eiko Sangyo Co., Ltd.

Example 13
[Production of fibers and cylindrical knitted fabrics]
An 80 dtex/48 f core-sheath composite polyester fiber and a tubular knit fabric were obtained in the same manner as in Example 12, except that the polyester resin obtained in Example 2 was used as the sheath.

Example 14
[Production of fibers and cylindrical knitted fabrics]
An 80 dtex/48 f core-sheath composite polyester fiber and a tubular knit fabric were obtained in the same manner as in Example 12, except that the polyester resin obtained in Example 3 was used as the sheath.

Example 15
[Production of fibers and cylindrical knitted fabrics]
An 80 dtex/48 f core-sheath composite polyester fiber and a tubular knit fabric were obtained in the same manner as in Example 12, except that the polyester resin obtained in Example 8 was used as the sheath.

Example 16
[Production of fibers and cylindrical knitted fabrics]
An 80 dtex/48 f core-sheath composite polyester fiber and a tubular knit fabric were obtained in the same manner as in Example 12, except that the polyester resin obtained in Example 9 was used as the sheath.

Example 17
[Production of fibers and cylindrical knitted fabrics]
An 80 dtex/48 f core-sheath composite polyester fiber and a tubular knit fabric were obtained in the same manner as in Example 12, except that the polyester resin obtained in Example 10 was used as the sheath.

Tables 1 and 2 show the production conditions, property values, and evaluation results of the polyester resins, sheets, and fibers obtained in the examples and comparative examples.

Table 3 shows details of the silicones used in the examples and comparative examples.

As is clear from Tables 1 and 2, the polyester resins obtained in Examples 1 to 11 had silicone copolymerized into the polyester resin and also had high reaction rates. This resulted in excellent spinning operability, and the resulting sheets and fibers (single-component polyester fibers and core-sheath composite polyester fibers) had excellent water repellency and water repellency durability.

On the other hand, the polyester resin obtained in Comparative Example 1 had a low content of copolymerized silicone, and therefore was inferior in water repellency and water repellency durability.
The polyester resin obtained in Comparative Example 2 had an excessively high content of copolymerized silicone, which resulted in frequent thread breakage during spinning and poor spinning operability.

The polyester resin obtained in Comparative Example 3 had a low reaction rate due to the small amount of dimethyltin oxide added as an esterification catalyst, and unreacted silicone remained in the resin as foreign matter, resulting in frequent yarn breakage during spinning and poor operability. Furthermore, the water-repellent durability was also poor.
The polyester resin obtained in Comparative Example 4 contained a large amount of dimethyltin oxide, an esterification catalyst, which caused decomposition of the silicone, and the decomposed silicone became a foreign substance in the resin, causing frequent yarn breakage during spinning and resulting in poor operability.The water repellency durability was also poor.

In Comparative Example 5, the esterification reaction temperature was as low as 240° C., so the reaction did not proceed sufficiently and a polyester resin could not be obtained, and therefore evaluation was not possible.
The polyester resin obtained in Comparative Example 6 had a high esterification reaction temperature of 280°C, which accelerated decomposition of the silicone, and the presence of silicone decomposition products in the resin turned into foreign matter, resulting in frequent yarn breakage during spinning and poor operability.The resin also had poor water repellency durability.

The polyester resin obtained in Comparative Example 7 had a low silicone reaction rate due to the small amount of tetrabutyl titanate added as a polycondensation catalyst, and the presence of unreacted silicone in the polyester resin resulted in foreign matter, which caused frequent yarn breakage during spinning and resulted in poor operability.The water repellency durability was also poor.
The polyester resin obtained in Comparative Example 8 contained a large amount of tetrabutyl titanate, a polycondensation catalyst, which caused decomposition of the silicone, and the decomposed silicone became a foreign substance in the resin, causing frequent yarn breakage during spinning and resulting in poor operability.The water repellency durability was also poor.

In Comparative Example 9, the polycondensation reaction temperature was low at 240°C, so the reaction did not proceed sufficiently and a polyester resin could not be obtained, making it unsuitable for evaluation.

In Comparative Example 10, the polycondensation reaction temperature was as high as 280°C, which accelerated the decomposition of the silicone, and the silicone decomposition products present in the polyester resin became foreign matter, resulting in frequent yarn breakage during spinning and poor operability. The product also had poor water-repellent durability.

Claims (7)

A polyester resin comprising a polyester made of an aromatic dicarboxylic acid and an aliphatic diol and silicone contained therein,
90% or more of the silicone is copolymerized with polyester;
the content of copolymerized silicone in the polyester resin is 1 to 60 mass %,
A polyester resin having an intrinsic viscosity of 0.5 to 0.8 . A fiber comprising the polyester resin according to claim 1 . A film comprising the polyester resin according to claim 1 . A molded article comprising the polyester resin according to claim 1 . A resin solution containing the polyester resin according to claim 1 . A powder containing the polyester resin according to claim 1 . A method for producing a polyester resin by carrying out an esterification reaction and a polycondensation reaction,
A mixture of polyester raw materials and silicone,
A tin-based esterification catalyst is added in an amount of 1×10 ⁻⁵ to 1×10 ⁻⁴ mol per mol of the total acid components of the polyester, and an esterification reaction is carried out at a reaction temperature of 250 to 270° C.,
A method for producing a polyester resin, comprising adding 1×10 ⁻⁵ to 1×10 ⁻⁴ mol of a polycondensation catalyst per 1 mol of the total acid components of the polyester, and carrying out a polycondensation reaction at a reaction temperature of 250 to 270°C.